Re: [RFC v2 0/6] x86: dynamic indirect branch promotion

[Nadav Amit]

> On Jan 3, 2019, at 10:10 AM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> 
> On Mon, Dec 31, 2018 at 07:53:06PM +0000, Nadav Amit wrote:
>>> On Dec 31, 2018, at 11:51 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>>> 
>>> On Sun, Dec 30, 2018 at 11:20 PM Nadav Amit <namit@xxxxxxxxxx> wrote:
>>>> This is a revised version of optpolines (formerly named retpolines) for
>>>> dynamic indirect branch promotion in order to reduce retpoline overheads
>>>> [1].
>>> 
>>> Some of your changelogs still call them "relpolines".
>>> 
>>> I have a crazy suggestion: maybe don't give them a cute name at all?
>>> Where it's actually necessary to name them (like in a config option),
>>> use a description like CONFIG_DYNAMIC_DEVIRTUALIZATION or
>>> CONFIG_PATCH_INDIRECT_CALLS or something.
> 
> Cute or not, naming is important.
> 
> If you want a description instead of a name, it will be a challenge to
> describe it in 2-3 words.
> 
> I have no idea what "dynamic devirtualization" means.
> 
> "Patch indirect calls" doesn't fully describe it either (and could be
> easily confused with static calls and some other approaches).
> 
>> Iâm totally fine with that (donât turn me into a "marketingâ guy). It was
>> just a way to refer to the mechanism. I need more feedback about the more
>> fundamental issues to go on.
> 
> Naming isn't marketing.  It's a real issue: it affects both usability
> and code readability.

Well, allow me to be on the fence not this one.

I look for the path of least resistance. I think it would be easiest if I
first manage to make Joshâs static calls to be less intrusive. For that, I
try to add in the GCC plugin an attribute to annotate the function pointers
whose calls should be promoted. However, I donât manage to get the
declaration from the call instruction's rtx. If anyone has a pointer on how
it can be done, thatâs would be very helpful.